为明确玉米叶绿素荧光特性对氮密互作的响应关系.采用二因素随机区组设计,主区为5个氮素处理,副区为3个种植密度.定株测定了叶片叶绿素荧光动力学参数.结果表明,叶绿素相对含量(SPAD)、初始荧光(F0)、最大荧光(Fm)、光能转换效率(Phi2)和线性电子传递流(LEF)对氮素用量的响应均呈现先升高后下降趋势,且峰值出现在135 N kg/hm2～180 N kg/hm2之间,氮素影响幅度依次为NPQt＞LEF＞NPQ＞Fm＞F0=SPAD＞Phi2=Fv/Fm.SPAD、NPQ、NPQt和LEF值均随密度提高而下降,在6.00×104株/hm2下较高;F0和Fm值则随密度提高而呈增高趋势,密度影响幅度依次为LEF＞NPQ＞NPQt＞F0＞SPAD＞Fm＞Fv/Fm＞Phi2.氮素对所有测定参数平均影响幅度小于密度.综上,在适量减氮增密条件下,叶绿素吸收光能后,能够更加高效地将光能传递至光合系统Ⅱ,提高了有效量子产量和非光化学猝灭反应强度,维持了较高的光能利用效率,本研究为提高玉米光能利用效率、充分发挥氮素和密度利用潜力提供理论依据.
Effects of Different Nitrogen Amount and Plant Density on Chlorophyll Fluorescence Characteristic of Spring Corn Hybrid
The purpose of this study was to clarify the response of maize chlorophyll fluorescence character to ni-trogen xdensity interaction.A two-factor random block design was adopted.The main plot was composed of five nitrogen treatments.In sub-plot,there were three planting density treatments.Chlorophyll fluorescence kinetic pa-rameters were determined by targeting plant.The results showed that the response of chlorophyll content(SPAD),initial fluorescence(F0),maximum fluorescence(Fm),effective quantum yield(Phi2),and linear electron flow(LEF)to nitrogen application increased firstly and then decreased.The peak value of nitrogen application ranged from 135 N kg/hm2～180 N/kg/hm2.The influence range of nitrogen was NPQt＞LEF＞NPQ＞Fm＞F0=SPAD＞Phi2=Fv/Fm.SPAD,NPQ,NPQt and LEF all decreased with the increase of density.The values of each parameter were higher at 6.00×104 plant/hm2,the values of F0 and Fm increased with the increase of density.The influence range of density was LEF＞NPQ＞NPQt＞F0＞SPAD＞Fm＞Fv/Fm＞Phi2.The total influence range of nitrogen on test parameters was less than those of density.In conclusion,reduce nitrogen application amount and increase density treatment moderately could transfer the light energy to the photosynthetic system Ⅱ more efficiently after the chlorophyll absorbs light energy,which could improve the effective quantum yield and non-chemical quenching reaction intensity,main-tained relatively high light energy utilization efficiency throughout the whole growth stage.The results provided theoretical basis for improving maize light utilization efficiency and giving full play to nitrogen and density utiliza-tion potential.
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